hello skiddow
well i do not use minergate and prob never will.
you have asked a question that has so many answers with so many varriables.
about the amd gpus and earning money well this is mostly dictated by pool , electrical price per kwh , your initial cost and the price of a coin that you are mining.
so if you ask me if it is profitable for you find out what you pay per kwh and check online to see what the avg hashrate is for the card you want to use and the coin you want to mine.
try filling these values in at sites like for example coinwarz or whattomine and you see if the chance is there to make a profit.
the other thing is do you have a dedicated machine or do you want to do mining only if you are not using the pc.
for the first i do have a easy to use option though.
Its called PiMP a full linux based realy easy to get into as a windows user dedicated mining OS, if you would need more information or have any other question about mining please come and join us on our irc channel #pimp on the freenode server
we have setup a special site for XMR aswell
https://getpimp.org/landing/how-to-mine-xmr-the-fastest-and-easiest-way/hope this clears things up for you
dbct